Example: Simple GUI

This example will show you how to create the simple GUI shown in the image above. The GUI contains one 3D view and two sliders for changing the parameters of two different algorithms, Gaussian smoothing and surface extraction. Changing the parameters will automatically trigger the algorithms to re-execute and the new result is displayed immediately in the 3D view. FAST uses Qt for the GUI, and several Qt elements such as QSlider, QLabel, QPushButton and QBoxLayout will be used in this example. A video of the example can be found on Youtube

First, the SimpleGUI class which represents a window. It extends the FAST Window object.

/**
 * Examples/GUI/SimpleGUI/SimpleGUI.hpp
 *
 * If you edit this example, please also update the wiki and source code file in the repository.
 */
#ifndef SIMPLE_GUI_HPP_
#define SIMPLE_GUI_HPP_

#include "FAST/Visualization/Window.hpp"
#include "FAST/Algorithms/SurfaceExtraction/SurfaceExtraction.hpp"
#include <FAST/Algorithms/GaussianSmoothingFilter/GaussianSmoothingFilter.hpp>
#include <QLabel>

namespace fast {

class SimpleGUI : public Window {
	FAST_OBJECT(SimpleGUI)
	public:
		void updateThreshold(int value);
		void updateSmoothingParameter(int value);
	private:
		SimpleGUI();

		SurfaceExtraction::pointer mSurfaceExtraction;
		GaussianSmoothingFilter::pointer mSmoothing;
		QLabel* mSmoothingLabel;
		QLabel* mThresholdLabel;
};

}

#endif

/**
 * Examples/GUI/SimpleGUI/SimpleGUI.cpp
 *
 * If you edit this example, please also update the wiki and source code file in the repository.
 */
#include "SimpleGUI.hpp"
#include <QVBoxLayout>
#include <QHBoxLayout>
#include <QPushButton>
#include <QSlider>
#include <FAST/Importers/ImageFileImporter.hpp>
#include <FAST/Visualization/MeshRenderer/MeshRenderer.hpp>
#include <boost/bind.hpp>

namespace fast {

SimpleGUI::SimpleGUI() {

	// Create a 3D view
    View* view = createView();
    view->set3DMode();

    enableFullscreen();

    // Import image
    ImageFileImporter::pointer importer = ImageFileImporter::New();
    importer->setFilename(std::string(FAST_TEST_DATA_DIR) + "/CT-Abdomen.mhd");

    // Smooth image
    mSmoothing = GaussianSmoothingFilter::New();
    mSmoothing->setInputConnection(importer->getOutputPort());
    mSmoothing->setStandardDeviation(1);

    // Set up surface extraction
    mSurfaceExtraction = SurfaceExtraction::New();
    mSurfaceExtraction->setInputConnection(mSmoothing->getOutputPort());
    mSurfaceExtraction->setThreshold(100);

    // Set up rendering
    MeshRenderer::pointer renderer = MeshRenderer::New();
    renderer->addInputConnection(mSurfaceExtraction->getOutputPort());
    view->addRenderer(renderer);

    // Create and add GUI elements

    // First create the menu layout
    QVBoxLayout* menuLayout = new QVBoxLayout;

	// Menu items should be aligned to the top
    menuLayout->setAlignment(Qt::AlignTop);

    // Title label
    QLabel* title = new QLabel;
    title->setText("Menu");
    QFont font;
    font.setPointSize(28);
    title->setFont(font);
    menuLayout->addWidget(title);

	// Quit button
    QPushButton* quitButton = new QPushButton;
    quitButton->setText("Quit");
    quitButton->setFixedWidth(200);
    menuLayout->addWidget(quitButton);

    // Connect the clicked signal of the quit button to the stop method for the window
    QObject::connect(quitButton, &QPushButton::clicked, boost::bind(&Window::stop, this));

    // Smoothing parameter label
    mSmoothingLabel = new QLabel;
    mSmoothingLabel->setText("Smoothing: 1.5 mm");
    menuLayout->addWidget(mSmoothingLabel);

    // Smoothing parameter slider
    QSlider* slider = new QSlider(Qt::Horizontal);
    slider->setMinimum(0);
    slider->setMaximum(3);
    slider->setValue(1);
    slider->setFixedWidth(200);
    menuLayout->addWidget(slider);

    // Connect the value changed signal of the slider to the updateSmoothingParameter method
    QObject::connect(slider, &QSlider::valueChanged, boost::bind(&SimpleGUI::updateSmoothingParameter, this, _1));

    // Threshold label
    mThresholdLabel = new QLabel;
    mThresholdLabel->setText("Threshold: 100 HU");
    menuLayout->addWidget(mThresholdLabel);

    // Threshold slider
    QSlider* slider2 = new QSlider(Qt::Horizontal);
    slider2->setMinimum(-100);
    slider2->setMaximum(300);
    slider2->setValue(100);
    slider2->setFixedWidth(200);
    menuLayout->addWidget(slider2);

    // Connect the value changed signal of the slider to the updateThreshold method
    QObject::connect(slider2, &QSlider::valueChanged, boost::bind(&SimpleGUI::updateThreshold, this, _1));

    // Add menu and view to main layout
    QHBoxLayout* layout = new QHBoxLayout;
    layout->addLayout(menuLayout);
    layout->addWidget(view);

    mWidget->setLayout(layout);
}

void SimpleGUI::updateThreshold(int value) {
	mSurfaceExtraction->setThreshold(value);

	// Update label
	std::string text = "Threshold: " + boost::lexical_cast<std::string>(value) + " HU";
	mThresholdLabel->setText(text.c_str());
}

void SimpleGUI::updateSmoothingParameter(int value) {
	// The slider can only use int values, must convert to float manually
	float standardDeviation = 1 + value*0.5;
	mSmoothing->setStandardDeviation(standardDeviation);

	// Update label
	std::string text = "Smoothing: " + boost::lexical_cast<std::string>(standardDeviation) + " mm";
	mSmoothingLabel->setText(text.c_str());
}

} // end namespace fast

Finally, the main function which instantiates the SimpleGUI object and starts the pipeline:

/**
 * Examples/GUI/SimpleGUI/main.hpp
 *
 * If you edit this example, please also update the wiki and source code file in the repository.
 */
#include "SimpleGUI.hpp"

using namespace fast;

int main() {

	SimpleGUI::pointer window = SimpleGUI::New();
	window->start();

	return 0;
}